Conventionally, JP-A-2009-94158 teaches a semiconductor device having an IGBT (i.e., insulated gate bipolar transistor) region, a diode region and a gate runner region. An IGBT is formed in the IGBT region. A diode is formed in the diode region. An emitter electrode and a surface pad for coupling with an external device are formed on a surface of the diode region. A wiring for the IGBT and a wiring for the diode are arranged on the gate runner region. The gate runner region is an outer periphery region of the IGBT region and the diode region so that the gate runner region is disposed on the outside of the IGBT region and the diode region. A P conductive type well is formed in a surface portion of a semiconductor substrate in the gate runner region. Further, a contact region having a P+ conductive type for reducing a resistance of the well is formed in a surface portion of the P conductive type well.
In the above structure, when the semiconductor device recovers, a hole accumulated in the gate runner region is removed to the outside via the contact region and an emitter electrode and the surface pad.
Accordingly, the hole is not concentrated at an end of the contact region in the IGBT region on a gate runner region side. Thus, the recovery breakdown is restricted.
However, in the above prior art, in order to easily remove the hole in the gate runner region, multiple contact regions having the P+ conductive type for reducing the resistance of the P conductive type well are formed. Thus, the recovery withstand of the semiconductor device is improved. However, the hole is concentrated at one of the contact regions having a low resistance because of the variation of the impurity concentration in the contact regions. Temperature of a place, at which the hole is concentrated, increases, so that recovery breakdown may occur at the place. Accordingly, in a structure having multiple contact regions, the recovery withstand is not obtained stably.
In the above case, the semiconductor device includes the IGBT. Alternatively, the semiconductor device may include a MOSFET or the like. In this case, a hole is accumulated in an outer periphery region. In this case, it is difficult to obtain the recovery withstand stably.